Constructing amphiphilic polymer brushes on the convex surfaces of multi-walled carbon nanotubes by in situ atom transfer radical polymerization

A fascinating nanoobject, amphiphilic polymer brushes with a hard core of multi-walled carbon nanotubes (MWNTs) and a relatively soft shell of polystyrene-block-poly(acrylic acid) (PS-b-PAA), was easily constructed by in situ atom transfer radical polymerization (ATRP) of styrene followed by tert-butyl acrylate on the modified convex surfaces of MWNTs (MWNT-PS) followed by hydrolysis of the grafted poly(tert-butyl acrylate) (PtBA) blocks. The structure and morphology of the as-prepared hybrid nanomaterials were characterized and confirmed by electron microscopy (TEM and SEM), nuclear magnetic resonance (NMR) spectrometry, and thermogravimetric analysis (TGA). The results showed that both styrene and acrylate types of ATRP-active vinyl monomers can be easily initiated and then propagated on the MWNT sidewalls via the in situ ATRP approach, and the length of the PtBA blocks increases with increasing tBA : MWNT-PS weight feed ratio. We believe that the breakthrough associated with formation of such a complex nanoobject would open a door for the fabrication of novel functional carbon nanotube-based nanomaterials or nanodevices with designable structure and tailor-made properties.